The $106bn merger of America Online and Time Warner has cleared its final government hurdle.
The Federal Communications Commission's approval lets the two companies forge ahead to complete a deal announced a year ago.
The new business, to be called AOL Time Warner, combines the largest US internet provider and a media titan that owns such popular entertainment titles as CNN, HBO, Sports Illustrated and Warner Bros.
The FCC approved the deal after requiring the companies to take modest steps to open AOL's widespread instant messaging service to rival providers over Time Warner's cable lines.
That issue caused protracted debate at the FCC, even though approval long has been expected.
Antitrust regulators at the Federal Trade Commission cleared the deal in December, but imposed broad restrictions to preserve consumer choice as the merged company gains a foothold in the markets for such services as high-speed internet access.
The FCC built on some of the conditions laid out at the FTC on the issue of internet access.
AOL was told by the FCC it will have to make its next generation of instant messaging services offered over Time Warner's cable lines available to competing systems. Those advanced services include video teleconferencing, the sharing of files or messaging over interactive television.
AOL rivals Microsoft, ExciteAtHome and AT&T had sought a broader condition forcing AOL to open its existing messaging service to all rivals.
The FCC also said it would take a closer look at ways to ensure cable companies will not steer viewers away from competitors in the emerging market for interactive television.